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- Mathematical modeling of gallic acid release from chitosan films with grape seed extract and carvacrolPublication . Rubilar, Javiera F.; Cruz, Rui; Zuñiga, Rommy N.; Khmelinskii, Igor; Vieira, M. M. C.Controlled release of antimicrobial and antioxidant compounds from packaging films is of utmost importance for extending the shelf-life of perishable foods. This study focused on the mathematical modeling of gallic acid release into an aqueous medium from three chitosan films, formulated with grape seed extract (GSE) and carvacrol. We quantified the release by HPLC technique during 30days at three temperatures (5, 25 and 45°C). The diffusion coefficients, varying with temperature according to an Arrhenius-type relationship, and the respective activation energies for Film-1 and Film-2 were, respectively [Formula: see text] m2s-1 and [Formula: see text] m2s-1, Ea1=58kJmol-1 and Ea2=60kJmol-1 as obtained from the Fickian fit. The low concentrations of gallic acid released by Film-3 could not be detected by HPLC, therefore the respective diffusion coefficient was not estimated. This study will help with the development and optimization of active packaging (AP) films aiming at improved food preservation and shelf-life extension.
- Preparation and characterization of a chitosan film with grape seed extract-carvacrol microcapsules and its effect on the shelf-life of refrigerated Salmon (Salmo salar)Publication . Alves, Vera Lúcia da Conceição Duarte; Rico, Bruna P. M.; Cruz, Rui; Vicente, António A.; Khmelinskii, Igor; Vieira, MargaridaChitosan films with grape seed extract and carvacrol microcapsules (CMF) were prepared and their physico-chemical properties and effect on physico-chemical and microbiological parameters in refrigerated salmon were tested. CMF showed higher values of thickness (0.41 ± 0.04 mm), moisture content (13 ± 1 g water/100 g film), a (11 ± 3), b (12 ± 3), opacity (20 ± 1%), water vapor permeability (WVP) (4.4 ± 0.4) × 10−10 gPa−1s−1m−1, oxygen permeability (O2P) (1.3 ± 0.3) × 10−12 gPa−1s−1m−1 and carbon dioxide permeability (CO2P) (1.3 ± 0.3) × 10−12 gPa−1s−1m−1 as compared to those of the chitosan control film (CCF). CMF showed lower values of L (66 ± 5) and water solubility (17 ± 1%). The salmon packed into CMF presented on the 7th day of storage a lower value of TVB-N (37 ± 4 mg N/100 g fish) as compared to the CCF (42 ± 3 mg N/100 g fish) and control samples (CS; 66 ± 7 mg N/100 g fish). The CMF showed lower values of pH and lightness after 7 days of storage as compared to CS and CCF. The CMF showed also lower values of mesophilic and psychrophilic bacteria and Pseudomonas spp, reaching the maximum limit allowed for the first two only on the 7th day of storage. CMF increases the shelf-life of refrigerated salmon to 4–7 days of storage due to the antimicrobial effect of the natural agents.